semver policy in readme

Author: scott-cotton

README.md

@@ -11,6 +11,10 @@ pal is in a volatile prototyping stage.  We have re-organised
 things a few times already, and there are many sizeable holes
 still to be coded.
 
+We will use v0.0.X semtags for this stage of development,
+and move to v0.1.X when the whole chain works together 
+well enough to be used by others on our tests.
+
 ## roadmap
 
 - cli